In a medium saucepan, combine maple syrup, butter, sugar, and egg over medium heat. Simmer mixture for 6 minutes, whisking constantly. Remove from heat, and stir in vanilla. Just before serving, stir in pecans. Serve warm.
Recipe by Southern Lady Magazine at https://southernladymagazine.com/sweet-potato-gingerbread-with-pecan-butter-sauce-recipe/